Stuck in Recovery mode after interrupted upgrade

Okay, so here's my problem.
So, yesterday I bought a used iPhone 3g, for half an hour or so I was stuck on the pineapple screen, possibly just because that was my first experience with an iPhone.

Now, when I finally got it in DFU mode, I connected it to a computer to upgrade from iTunes, this went well, until the update was interrupted since the laptop ran out of power.
After this, the phone would boot to an apple logo.

Now, third time, I tried upgrading again, this time, my dad pulled the chord out in the middle, and now whenever I try to upgrade (Even in DFU mode) I just get a 1015 (Trying to downgrade) error.

Also, whenever I start the iPhone (Except when I put it into DFU, ofcourse) I get stuck on the recovery screen, I looked up how to get out of it, but it doesn't work. Appearently I'm in a "Recovery screen loop".

Now, what should I do? Is my phone unusuable now?
Also, the previous owner resetted it, so it's not jailbroken.

Entering DFU Mode (Official Instructions)
Plug your device into your computer.
Turn off the device.
Hold the Power button for 3 seconds
Hold the Home button without releasing the Power button for 10 seconds
Release the Power Button but keep holding the Home button
Keep holding the Home button until you are alerted by iTunes saying that it has detected a device in Recovery Mode
Make sure the device screen is blank and no logos are present

Ugh, I got it to work by using iReb, and it worked fine for a while.
I then decided to jailbreak using Redsn0w, and in the guide I saw, it told me to restore to 4.2.1, now, foolish as I was, I thought that I could just do that and get it out with iReb again, now, ofcourse I got into a recovery loop again, but this time, iReb doesn't work!.
What shoudl I do? D:

EDIT: Never mind, forgot to downgrade to 4.1 first, it works again now, thanks. =P

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